Computerized Axial Tomography apparatus, commonly referred to as CAT or CT scanner devices, have proven to be of particular value in detection of cancer and other life-threatening conditions. Images obtained using CT scanners can help the diagnosing physician to visualize and localize an area of pathological tissue. However, in many cases, a biopsy of this tissue is then needed in order to provide an accurate diagnosis. Tissue samples are commonly obtained by puncturing the skin of the patient with a biopsy needle, guiding the needle to the site of the suspected tumor, and withdrawing a sample of the tissue.
Even with the help of a CT scan image that identifies the location of pathological tissue, however, it can be difficult to obtain a tissue sample from the suspected area. Lesions can be quite small and it can be extremely difficult to guide the biopsy needle to the proper penetration depth and angle needed. In response to this difficulty, one useful technique for obtaining a tissue sample from a suspected lesion is the CT-guided biopsy. In this technique, CT scanning or CT fluoroscopy is used as feedback to help position a biopsy needle to the proper location for extraction of a tissue sample.
Even though it uses CT imaging capabilities for biopsy needle positioning, CT-guided biopsy can be an iterative process. The biopsy needle is inserted to the approximate location, then a localized CT scan or a CT fluoroscopic image of this area is obtained as feedback on needle position, angle, and depth. The image that has been obtained is then used as a guide to readjust and correct needle position. With each iteration, the biopsy needle may be repositioned in the patient. Even with local anesthetics, this iterative procedure can be painful and uncomfortable for the patient as well as costly and time-consuming. Movement of the patient can inadvertently cause the needle to be shifted in position, requiring repetition of the sampling process. Moreover, each repeated scan increases the radiation risks to the patient and, particularly with CT fluoroscopy, to the radiologist, nurse, or CT operator.
In an effort to alleviate the positioning problem and provide stabilizing means for the biopsy needle, some types of CT devices have been outfitted with positioning components. However, these solutions have not satisfactorily resolved the positioning problem and, in a large number of cases, go unused. Alternately, there have been a number of solutions proposed for devices that assist in needle placement and positioning. A few examples of needle stabilization apparatus are the following:                U.S. Patent Application Publication No. 2004/0260312 entitled “Guide for a Medical Device” by Magnusson et al. describes a needle guide supported by a retainer for maintaining a needle or other medical instrument at a suitable position and angle.        U.S. Pat. No. 4,733,661 entitled “Guidance Device for C.T. Guided Drainage and Biopsy Procedures” to Palestrant describes a device for needle positioning that includes a support arm provided in a protractor-like arrangement and equipped with various devices to aid in proper needle orientation.        U.S. Pat. No. 4,883,053 entitled “Self-Supporting Angulator Device for Precise Percutaneous Insertion of a Needle or Other Object” to Simon describes a collapsible device that can be placed against the patient, the device having hinged sections that cooperate with a bracket to obtain the desired angular orientation of a needle.        U.S. Pat. No. 5,354,283 entitled “Trocar Retention Apparatus” to Bark et al. describes a stabilizing apparatus for this type of inserted instrument, using a base that supports a rotatable spheroid element for allowing the adjustment of angular movement of the instrument.        
A number of patent disclosures describe needle positioning devices for various types of medical procedures, where the devices use some type of protractor mechanism to adjust a needle holder to a specific angle over some range of angles. For example: U.S. Pat. No. 4,841,967 entitled “Positioning Device for Percutaneous Needle Insertion” to Chang et al.; U.S. Pat. No. 5,941,889 entitled “Multiple Angle Disposable Needle Guide System” to Cermak; and U.S. Pat. No. 5,201,742 entitled “Support Jig for a Surgical Instrument” to Hasson show this type of arrangement.
Each of these solutions, however, has its drawbacks. Many of the devices described in the above-cited patent literature are mechanically complex, making them difficult to use and to adapt to different areas of the body. For example, a number of these conventional devices employ spherical ball-and-socket mechanisms or have protractor arms for obtaining precision angular adjustments. Only a small number of these proposed solutions could be provided inexpensively as a sterilized, disposable item.
Considering the complexity of the CT-guided biopsy, it is well recognized that a device for stabilizing needle position should be easy to use, allowing the medical team to concentrate on safely and expeditiously performing this task. Since the CT-guided biopsy typically involves the iterative process described earlier, a needle stabilizing apparatus should allow good visibility of the skin area and should allow ease of readjustment, which are not features shared by many of the devices cited above. A needle stabilizing device should be as compact as possible and should be readily adaptable for use on different areas of the skin.